The present invention relates generally to adjustable devices, such as amplifiers for example, which convert a command signal to an appropriate control signal in order to control a mechanism according to parameters stored in the amplifier. More specifically, the present invention relates to a method and apparatus for modifying parameters of a valve amplifier such that it achieves the desired command-signal-to-control-signal conversion for controlling a valve.
Proportional solenoid valves are typically controlled by a valve amplifier, wherein an input command signal from a controller causes magnetically actuated movement of a slidable member in the valve, causing a flow path in the valve to become more open or more closed, thereby affecting fluid flow. This input command signal from the controller is usually a voltage signal between 0 and 10 volts, 0 volts corresponding to no flow and 10 volts corresponding to full flow. An example of a solenoid valve is provided in U.S. Pat. No. 5,242,149, the entire disclosure of which is hereby incorporated herein by reference.
However, a solenoid valve cannot respond directly to this voltage command, because each valve requires an electrical current which is between its minimum electrical current value (e.g., no flow) and its maximum electrical current value (e.g., maximum flow). Thus, in order for the valve to operate, a conversion device, such as an amplifier for example, is required to convert the voltage command signal from the controller to the appropriate electrical current control signal for the valve. For example, a voltage command signal which represents 50% flow (e.g., a 5 volt command signal) needs to be converted to the appropriate electrical current by the valve amplifier. In other words, the amplifier provides a control signal to the valve which is proportional to the input command signal. An example of such an amplifier is the PVG mobile valve amplifier, manufactured by Danfoss Fluid Power.
Valve amplifiers have also had the capability to be modified for the particular controller and valve with which they will be used. Parameters which affect the voltage-command-signal-to-electrical-current-control-signal conversion can include the ramp time, deadband, gain, maximum amplitude, and dither frequency, for example. The parameters are adjusted according to the particular valve with which the amplifier is used, and the particular application in which the valve is used.
For some amplifiers, the parameters can be adjusted by adjusting potentiometers provided in the amplifier circuitry. However, if the amplifier is digitally programmable, the amplifier can be provided with a connector, such as a serial connector, which can connect the programmable digital controller within the amplifier to a personal computer (PC) or other digital programming apparatus. Software on the PC can then adjust the parameters which affect the voltage-command-signal-to-electrical-current-control-signal conversion. Parameters can be downloaded from the PC to the amplifier, or uploaded from the amplifier to the programming apparatus and stored in a file. An example of such a programmable amplifier is described in U.S. Pat. No. 5,638,863, the entire disclosure of which is hereby incorporated herein by reference. Such an amplifier is described in the patent as including a microcomputer, a memory, and a separate interface for connecting to an external personal computer. When the computer is connected to the microcomputer through the interface, new parameters can be written to the memory of the amplifier.
Another example of a programmable or adjustable amplifier is available under the trade name EMA amplifier, which is manufactured by Vickers Incorporated for controlling the EMV-611e valve. Windows-based software can be used for setting parameters and showing amplifier status via a PC, which can be connected using a serial connector on the amplifier. The software on the PC digitally sets ramp, deadband, gain and dither, which can be saved by a filename and recalled and used for various machine types. This amplifier requires a separate interface for receiving the command signal input from a controller.
Another programmable amplifier which has been developed is described in U.S. Pat. No. 5,172,311, issued to Reinhart et al. This amplifier includes a programmable component including a read-only-memory in which the amplifier is associated to a particular type of valve by loading the read-only-memory with valve specific data which specify a valve type. The programmable component of the amplifier comprises a microprocessor, a random access memory, and a separate interface for series transfer of data to and from a computer. Data transmitted through the interface to program the amplifier is stored in the random access memory.
However, while the programmable capability of such amplifiers can be advantageous, such amplifiers require an extra connector or interface for connecting to the programming apparatus (e.g., a computer). In addition, they require various components to allow the amplifier to communicate with the programming apparatus. As can be understood, this extra hardware adds to the cost of the amplifier and its complexity, and also takes up additional space. Moreover, the additional connector can compromise the environmental seal of the amplifier, which often needs to meet demanding standards.
Accordingly, it is desirable to provide a method and apparatus for programming parameters of a programmable device without requiring the device to include a separate interface, other than the interface which is already used to receive command signals, such that cost and complexity of the device are not increased, and the environmental rating is not compromised. Moreover, it is desirable to provide a method and apparatus for programming parameters of a programmable device without the necessity of providing the device itself with the programming components, which can add to its cost and complexity. Preferably, the programmable device can comprise an amplifier, such as a valve amplifier for example, which can convert a command signal to an appropriate control signal, for control of a controllable mechanism, such as a valve for example.
It is an object of the present invention to obviate the above-described problems.
It is a further object of the present invention to provide a method and apparatus for programming a programmable or adjustable device, such as a valve amplifier for example, without the necessity of providing the device with a separate interface for connection to a programming apparatus, such as a personal computer or microcontroller for example.
Yet another object of the present invention is to provide a method and apparatus for programming a device, without the necessity of providing the device with additional programming components.
Another object of the present invention is to provide a method and apparatus for connecting a valve amplifier to a computer, or other programming apparatus, without the necessity of providing the amplifier with an additional input connector.
It is yet another object of the present invention to provide a method and apparatus for programming a valve amplifier while providing the amplifier with a good resistance to environmental contaminants.
It is a further object of the present invention to provide an apparatus for programming a valve amplifier without the necessity of a personal computer or other digital programming device and without the necessity of providing the amplifier with a separate input connector/interface.
Another object of the present invention is to provide a valve amplifier adapter which can be connected to a valve amplifier when programming of the amplifier is required, but which can be removed from the amplifier when the amplifier is to control a valve.
Yet another object of the invention is to provide a method for programming a valve amplifier which does not require the amplifier to include a separate connection for the programming apparatus.
It is another object of the present invention to provide a method for programming a valve amplifier which reduces the amount of hardware required per amplifier.
Another object of the invention is to provide an adapter which can be used for programming multiple programmable or adjustable devices, such as multiple valve amplifiers for example.
Yet another object of the present invention is to provide a programming adapter which can be used for viewing and/or editing of parameters stored on a programmable device.
To achieve the foregoing and other objectives, an adapter for programming parameters is provided, comprising a first connector, a second connector, a programming circuit, an input device, and a display device. The first connector is configured to connect to a mating connector having conductors connecting to a valve, a valve controller, and a power supply. The second connector is configured to connect to a valve amplifier, and the programming circuit is adapted to generate and send modified parameters to the valve amplifier. The input device is adapted to provide inputs to the programming circuit, and the display is in communication with the programming circuit and adapted to display data from the programming circuit.
According to another aspect, a system for selectively programming an adjustable device is provided, comprising an adjustable device having a command signal connector adapted to receive a command signal from a controller, and a memory unit containing stored data. The system also includes a programming apparatus adapted to provide a programming instruction, and an adapter connecting the programming apparatus to the command signal connector of the adjustable device. The adjustable device is adapted recognize the difference between a programming instruction and a command signal, and to allow modification of the stored data only in response to the programming instruction.
In another aspect, a method of programming an adjustable device is provided. The adjustable device has a command signal input adapted to receive a command signal from a controller. The method comprises the steps of providing a command signal from a controller to a command signal input of an adjustable device, and disconnecting the command signal from the command signal input. The method also comprises the steps of detecting a programming mode, connecting a programming apparatus to the command signal input, and transmitting a programming command from the programming apparatus to the command signal input. In addition, the method comprises storing data in the adjustable device, after detecting the programming mode and transmitting the programming command.
Still other objects of the present invention will become apparent to those skilled in this art from the following description wherein there is shown and described preferred embodiments of this invention, including a best mode currently contemplated for carrying out the invention, simply for the purposes of illustration. As will be realized, the invention is capable of other different aspects and embodiments without departing from the scope of the invention. Accordingly, the drawings and descriptions are illustrative in nature and not restrictive in nature.